Sensor platform

ABSTRACT

Provided is an FET-type sensor array. In the FET-type sensor array, a plurality of FET-type sensors are arranged at arbitrary distances from one reference point, and the same areas of the FET-type sensors are arranged to face the reference point. The FET-type sensors includes a control electrode, a floating electrode, a sensing material layer arranged between the control electrode and the floating electrode, and source and drain regions formed on both sides of a lower portion of the floating electrode. In the FET-type sensor array, through miniaturisation of FET-type sensors constituting the sensor array and new design of air layers in the peripheries of micro-heaters built in the sensors and sensing material layers, power consumption of the micro-heaters can be reduced. In addition, the sensors can be efficiently arranged to reduce the area occupied by the sensor array, and the sensing material can also be heated by the adjacent micro-heaters, so that the total power consumption can also be reduced.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an FET-type sensor array, and moreparticularly, to an FET-type sensor array including silicon-based MOSFET(metal-oxide-semiconductor field-effect transistor) type sensors havinga floating electrode formed in a horizontal direction on a controlelectrode, an FET-type sensor array including FET-type sensors having abuilt-in micro-heater, and a method of manufacturing the same capable ofensuring thermal and mechanical stability and greatly reducing size andtotal power consumption through creative and efficient arrangement ofthe sensors and being applied to sensors for sensing various gases.

2. Description of the Related Art

In recent years, gas sensors having various structures have beendeveloped to sense various gases including harmful gases which causeenvironmental problems. As the gas sensors, there may be exemplifiedresistance-type gas sensors having a semiconductor as a sensingmaterial, gas sensors using an infrared ray, optical gas sensors, andFET-type gas sensors. Particularly, among these gas sensors, theFET-type gas sensors capable of being miniaturized, operating with lowerpower, and being incorporated with CMOS circuits such as low noiseamplifying circuits have been increasingly studied.

In the field of the gas sensor array, most of the gas sensor arrays thatare used to distinguish, various gases by using a pattern recognitioncircuit or software are mainly based on resistance-type gas sensors inthe related art on which different sensing materials are deposited. Onthe other hand, during the gas sensing, gas sensing characteristics arechanged depending on a change of external environment such as aconcentration of gas and an ambient temperature as well as a gas type.Particularly, the ambient temperature is a factor affecting gassensitivity and gas reaction and recovery speeds.

A gas sensor has the optimum temperature at which the sensitivity of thegas sensor is maximized for each gas sensing material and each kind ofgas to be sensed. In general, the higher the ambient temperature, thefaster the gas reaction and the recovery speeds. In the field of the gassensors array in the related art, studies of improving gas sensingcharacteristics by introducing various types of heaters have been made.

The FET-type sensors can foe applied mainly to gas sensing. Besides, theFET-type sensors can be applied to other types of sensing (for example,fine particle sensing, heavy metal sensing, and the like).

US Patent Application Publication No. US 2006/0187279 A1(PatentDocument 1) discloses a gas sensor array where resistance-type gassensors having a semi conductive metal oxide as a sensing material arearranged at a constant interval. Each gas sensor is provided with amicro-heater that can control an ambient temperature during gas sensingand a temperature sensor that can sense the ambient temperature.However, the gas sensors constituting the gas sensor array are of aresistance-type, and the distance between the gas sensors isconsiderably large, so that the total area is large.

In addition, since the gas sensor has a relatively large resistance-typestructure, power consumption is increased to heat, a sensing materiallayer of the gas sensor.

Korean Patent Laid-Open Publication No. 2013-0052528 (Patent Document 2)illustrates a basic structure and advantages of an FET-type gas sensorconstituting a gas sensor array proposed by the invention. The FET-typegas sensor disclosed in Patent Document 2 has a basic structure where acontrol electrode and a floating electrode are formed in a horizontaldirection, a sensing material layer is located therebetween, and amicro-heater and an air layer are arranged near the control electrode.On the basis of the structure, the FET-type gas sensor uses a change inwork function, a change in capacitance according to a change indielectric constant, charge generation/extinction, electromotive forcegeneration, and the like as sensing mechanisms.

The FET-type gas sensor disclosed in Patent Document 2 can significantlyreduce power consumption in comparison with sensors in the related artand can sense various types of gases accurately by changing the sensingmechanisms even if the same gas sensing material is used. In addition,since the sensing material is formed in the final stage of devicefabrication, there is no problem in that contamination problems occur.In the FET-type gas sensor having the above-mentioned structuredisclosed in Patent Document 2, it is possible to solve the problems ofthe FET-type gas sensor having the floating electrode and the controlelectrode and the sensing material layer formed in the verticaldirection in the related art. Namely, it is possible to solve theproblems such as a low coupling ratio between a control electrode and afloating electrode due to a parasitic capacitance component, low sensingsensitivity, and large power consumption, and high manufacturing costcaused from complexity of processes.

However, in the above-mentioned patents, the structures and the expectedeffect of the arrangement, of the gas sensors are very brieflydescribed.

Accordingly, the present invention proposes specific and efficientarrangement of a gas sensor array including FET-type gas sensors havinga horizontal floating electrode and efficient design of a micro-heaterand an air layer built, in each gas sensor. The array structureaccording to the invent ion can significantly reduce total area andtotal power consumption in comparison with the gas sensor arrays in therelated art.

Korean Patent Laid-Open Publication No. 2014-010633 (Patent Document 3)discloses a three-dimensional Fin-FET-type gas sensor. Thethree-dimensional Fin-FET-type gas sensor is formed so that a floatingelectrode is formed to surround a semiconductor body protruding in a FINshape to enlarge a width of a channel to increase a drain current, sothat the Fin-FET-type gas sensor has an advantage of increasing thesensitivity of the sensor.

Non-Patent Document 1 is “Micro-machined gas sensor array based on metalfilm micro-heater,” Yaowu Mo et al., Sensors and Actuators B: Chemical,pp. 175-181, No. 79, 2001. The gas sensor array introduced in Non-PatentDocument 1 is configured with eight resistance-type gas sensors, andeach gas sensor has a micro-heater in which titanium (Ti) and platinum(Pt) are deposited in this order. As a sensing material, tin oxide(SnO₂) is used, and it was found that the sensing material has aselectivity for ethanol (C₂H₅OH). Unlike the studies in the related art,an air layer for reducing loss of heat of the micro-heater is formed notfrom a backside of a substrate, but the air layer is formed throughanisotropic silicon etching of the silicon from a top side of thesubstrate to improve thermal characteristics. On the other hand, sincethe gas sensor has a resistance-type structure, the area occupied by thesensing material layer is 50 μm×50 μm in order to solve the problem ofproduction yield. Therefore, e power consumption of the micro-heater forheating the sensing material layer and the size of the gas sensor arrayincluding eight gas sensors are very large, 2 mm×4 mm.

Non-Patent Document 2 is “Room temperature multiplexed gas sensing usingchemical-sensitive 3.5-nm-thin silicon transistors”, Hossain MohammadFahad et al., Science Advances, e1602557, No. 3, 2017. In Non-PatentDocument 2, a gas sensor constituting a gas sensor array has an FET-typestructure where a silicon substrate having a bundle of thin siliconchannels is as a control electrode, and the silicon channels are dopedwith metal substances such as palladium (Pd), nickel (Ni), and gold (Au)to analyse sensing characteristics of various gases. In addition,micro-heaters where chrome (Cr) and gold (Au) are sequentially depositedare formed in the periphery of the gas sensors, and thus, desorptionrates of gases adsorbed to the sensing material layers are improved byheating the micro-heaters. However, there is no air layer for preventingloss of heat generated by the micro-heaters, and the micro-headersoccupies a large area around the gas sensors, and thus, the powerconsumption is unnecessarily large. In addition, the size of the gassensor array is also very large.

Therefore, development of a newly designed gas sensor array capable ofsolving the problems of the gas sensor arrays in the related has beenrequired.

SUMMARY OF THE INVENTION

The invention is proposed to solve disadvantages of a sensor-arrayincluding a plurality of resistance-type sensors or FET-type sensors inthe related art such as an unnecessarily large size of the sensor array,large power consumption of micro-heaters, and high manufacturing costcaused from complexity of processes. The invention is to provide anefficient arrangement of an FET-type sensor having a horizontal floatingelectrode constituting a sensor array and an efficient structure of amicro-heater and an air layer.

According to an aspect of the invention, there is provided an FET-typesensor array including a plurality of FET-type sensors which arearranged at arbitrary distances from one reference point, wherein theFET-type sensor includes: a semiconductor substrate; a semiconductorbody formed to protrude from the semiconductor substrate; an isolationinsulating film formed on a side surface of the semiconductor body; agate insulating film formed on the semiconductor body; a floatingelectrode formed on the gate insulating film and the isolationinsulating film; a protective insulating film formed at least on thefloating electrode; a control electrode formed to face and behorizontally separated from at least one side surface of the floatingelectrode; a sensing material layer arranged on the control electrodeand at least horizontally opposing sidewalls of the floating electrode,the sensing material layer being arranged to the floating electrode withthe protective insulating film interposed therebetween; and source/drainregions formed in the semiconductor body with the floating electrodeinterposed therebetween, and wherein the same areas of the FET-typesensors are arranged to face a reference point.

In the FET-type sensor array according to the above aspect, the sensingmaterial layers of a plurality of the FET-type sensors may be made of aplurality of sensing materials having different compositions, and eachsensing material may be applied to one or two or more FET-type sensors.

In the FET-type sensor array according to the above aspect, the controlelectrode may be formed on the isolation insulating film to have aspecific length and be used as a micro-heater, the protective insulatingfilm may be formed at least on the floating electrode and the controlelectrode, and the FET-type sensor may further include an air layerformed at least below the isolation insulating film that is in contactwith the control electrode.

In the FET-type sensor array according to the above aspects, the controlelectrodes used as the micro-heaters of a plurality of the FET-typesensors may be arranged to be adjacent to each other, and thus, thesensing material layer in each FET-type sensor is heated by the controlelectrode of each FET-type sensor and the control electrode of theadjacent FET-type sensor, or the control electrode used as themicro-heater of each FET-type sensor is formed to face a referencepoint, so that power consumption is reduced.

In the FET-type sensor array according to the above aspect, the controlelectrodes of a plurality of the FET-type sensors may be connected toeach other in series or in parallel, or some of the control electrodesmay be connected to each other in series and the others of the controlelectrodes are connected to each other in parallel; and line widths ofthe control electrodes used as the micro-heaters may be equal to eachother or the line width may be changed depending on each FET-typesensor.

In the FET-type sensor array according to the above aspect, the linewidths of the sensing material layers and the control electrodes in theperipheries thereof in the sensor array are formed to be smaller thanthe line widths of the control electrodes in the remaining areas, andthe FET-type sensor may further include metal wires which are inelectric contact with the control electrodes and a plurality of contactholes which are formed between the control electrodes and the metalwires.

In the FET-type sensor array according to the above aspect, the FET-typesensor may further include an undercut pattern for forming the airlayer, and the undercut pattern may be formed to have one of shapesincluding a circle, an ellipse, a square, a square having roundedcorners, a rectangle, a rectangle having rounded corners or maybe formedto have one of shapes including an ellipse, a rectangle, and a rectanglehaving rounded corners and include one or two regions that are bent atarbitrary angles in the middle.

The sensor array according to the invention basically includes aplurality of FET-type sensors having a floating electrode formed in anupper portion of a semiconductor body in which a channel is formed and asensing material layer and a control electrode arranged in a horizontaldirection thereof. At this time, the semiconductor body is formed toprotrude from the semiconductor substrate, and an isolation insulatingfilm is formed on a side surface of the semiconductor body. Amicro-heater isolated by an isolation insulating film may be included inthe periphery of the control electrode and the sensing material layer ofthe FET-type sensor, and Anisotropic etching of the Isolation insulatingfilm and isotropic etching of the semiconductor substrate may besequentially performed to provide an air layer below the micro-heater.

The FET-type sensors constituting the sensor array according to theinvention has micro-heaters made of a metal or polycrystalline siliconhaving high thermal conductivity and high electric conductivity in theperiphery of the control electrode and the sensing material layer. Inthis case, the micro-heater is arranged in the horizontal direction withrespect to the floating electrode, and in the case where themicro-heater and the floating electrode are formed with the samematerial, the micro-heater can be formed without additional mask andprocess.

In the FET-type sensor constituting the sensor array according to theinvention, after forming the control electrode, the isolation insulatingfilm and the semiconductor substrate in the periphery of the sensingmaterial layer are etched by additionally using a mask to form an airlayer below the micro-heater. At this time, the air layer may be locallyformed only in the periphery of the sensing material layer, so that, itis possible to minimize loss of heat of the micro-heater and to reducepower consumption.

The sensor array according to the invention may have independentmicro-heaters or micro-heaters connected as a single micro-heater. Whenthe micro-heaters are arranged in a plurality of the sensors in thesensor array, the micro-heaters of the sensors are arranged to be closeto each other, and thus, it is possible to provide a structure that canbe sufficiently heated by the micro-heaters of the adjacent sensors aswell as the micro-heaters built in the sensors, so that it is possibleto obtain the effect of reducing power consumption.

The line widths of the micro-heaters built in the FET-type sensorsconstituting the sensor array according to the invention can bearbitrarily adjusted. Since the maximum sensitivity of a sensingmaterial applied to a sensor may be different depending on a heatertemperature, by selecting the line width of the micro-heater suitablefor the optimum temperature of reaction of each sensing material, it ispossible to increase the sensitivity and to reduce power consumption.

In the FET-type sensors constituting the sensor array according to theinvention, the line widths of the micro-heaters arranged in the regionsother than the sensing material layers and the peripheries thereof areincreased, so that it is possible to minimize the heat generation, andair layers are formed, so that it is possible to reduce loss of heat andpower consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary equivalent circuit diagram illustrating a sensorarray where a plurality of FET-type sensors are arranged in rows andcolumns as an example of a sensor array in the related art;

FIGS. 2A to 2D illustrate an FET-type sensor having a horizontalfloating electrode in the related art, FIG. 2A is a plan view, FIG. 2Bis across-sectional view taken along line A-A′ in FIG. 2A, FIG. 2C is across-sectional view taken along line B-B′, and FIG. 2D is across-sectional view of a three-dimensional Fin-FET-type sensor as amodified form of FIG. 2B;

FIG. 3 is an exemplary equivalent circuit diagram illustrating a sensorarray where a plurality of FET-type sensors including a micro-heater andan air layer are arranged in rows and columns as an example of a sensorarray in the related art;

FIGS. 4A to 4D illustrate an FET-type sensor in the related art as amodified form of the sensor illustrated in FIG. 2A, FIG. 4A is a planview, FIG. 4B is across-sectional view taken along line A-A′ in FIG. 4A,FIG. 4C is a cross-sectional view taken along line B-B′, and FIG. 4D isa cross-sectional view of a three-dimensional Fin-PET-type sensor as amodified form of FIG. 4B;

FIGS. 5A to 5D illustrate examples of a sensor arrangement method of thesensor array according to the invention, FIG. 5A is an equivalentcircuit diagram illustrating a case where sensors are arranged on acircle to be separated from each other at an arbitrary angle, FIG. 5B isan equivalent circuit diagram illustrating a case where sensors arearranged on an ellipse, FIG. 5C is an equivalent circuit diagramillustrating a case where sensors are arranged on a rectangle, and FIG.5D is an equivalent circuit diagram illustrating a case where the sameareas of the FET-type sensors arranged on a rectangle face a referencepoint and are deviated by arbitrary angles from lines connecting thereference point and the centers of the FET-type sensors;

FIGS. 6A to 6G illustrate examples of a sensor arrangement method of thesensor array according to the invention, FIG. 6A is an equivalentcircuit diagram illustrating a case where sensors having a built-inmicro-heater are arranged on a circle to be separated from each other atan arbitrary angle, FIG. 6B is an equivalent circuit diagramillustrating a case where sensors having a built-in micro-heater arearranged on an ellipse and the heaters are connected in series, FIG. 6Cis an equivalent circuit diagram illustrating a case where sensorshaving a built-in micro-heater are arranged on an ellipse and theheaters are arranged in parallel, FIG. 6D is an equivalent circuitdiagram illustrating a case where sensors having a built-in micro-heaterare arranged on a rectangle and the heaters are connected in series,FIG. 6E is an equivalent circuit diagram illustrating a case wheresensors having a built-in micro-heater are arranged on a rectangle andthe heaters are arranged in parallel, FIG. 6F is an equivalent circuitdiagram illustrating a case where sensors having a built-in micro-heaterare arranged on a rectangle, the heaters are connected in series, andthe heaters face a reference point and are deviated by arbitrary anglesfrom lines connecting the reference point and the centers of theFET-type sensors, and FIG. 6G is an equivalent circuit diagramillustrating a case where sensors having a built-in micro-heater arearranged on a rectangle, the heaters are connected in parallel, and theheaters face a reference point and are deviated by arbitrary angles fromlines connecting the reference point and the centers of the FET-typesensors;

FIGS. 7A and 7B illustrate FET-type sensors having a horizontal floatingelectrode in the related art constituting a sensor array according tothe invention, FIG. 7A is a plan view illustrating a case where a sourceelectrode and one-end electrode of a micro-heater are separated, andFIG. 7B is a plan view illustrating a case where a source electrode andone-end electrode of a micro-heater are shared;

FIGS., 8A and 8B illustrate modified examples of the sensors illustratedin FIGS. 7A and 7B, respectively, and are plan views illustrating caseswhere line widths of the micro-heaters arranged in the regions otherthan the sensing material layers and the peripheries thereof areincreased;

FIGS. 9A and 9B illustrate modified examples of the sensors illustrated,in FIGS. 8A and 8B, respectively, and are plan views illustrating caseswhere the number of contact holes of the micro-heater is increased;

FIGS. 10A and 10B illustrate modified examples of the sensorsillustrated in FIGS. 9A and 9B, respectively, and are plan viewsillustrating cases where materials having a thermal conductivity lowerthan that of a metal are connected to have a certain length throughcontact holes provided at both ends of a control electrode which is madeof a metal and metal wires are connected through contact holes providedat both ends of each material having low thermal conductivity;

FIGS. 11A and 11B illustrate modified examples of the sensorsillustrated in FIGS. 10A and 10B, respectively, and are plan viewsillustrating cases where undercut patterns are formed as close aspossible to a micro-heater and anchors are formed between the patterns;and

FIGS. 12A and 12B illustrate examples of a sensor arrangement method ofa sensor array according to the invention having a structure in whichsensors are arranged as close as possible so as to be sufficientlyheated by the micro-heaters of the adjacent sensors, FIG. 12A is a planview illustrating a case where the sensor array is configured withsensors having the same sensing material and micro-heaters having thesame line width, and FIG. 12B is a plan view illustrating a case wherethe sensor array is configured with sensors having different sensingmaterials and micro-heaters having different line widths.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated in FIG. 1, unlike the related art. where sensors arearranged in arbitrary intervals of rows or/and columns, a sensor arrayaccording to a first embodiment of the invention is configured toinclude a plurality of FET-type sensors SO arranged at arbitrarydistances from one reference point, and the same area 630 (for

example, a control electrode) of each FET-type sensor 80 is formed toface the reference point. The same area may be a control electrode ormay be a control electrode that can be used as a micro-heater.

The FET-type sensor SO is an FET-type sensor 80 having a horizontalfloating electrode 300 disclosed in Patent Documents 2 and 3. TheFET-type sensors 80 include sensors illustrated in FIGS. 2A to 2D wherea change in dielectric constant of a sensing material layer 40 accordingto presence or absence of a to-be-sensed material is used as anoperation sensing mechanism or a change in work function is used as anoperation sensing mechanism.

In particular FIG. 2D illustrates a structure of a three-dimensionalFin-FET-type sensor disclosed in Patent Document 3. Thethree-dimensional Fin-FET-type sensor is configured to include asemiconductor substrate 100, a semiconductor body 110 formed to protrudefrom the semiconductor substrate 100, an isolation insulating film 200formed on a side surface of the semiconductor body 110 and thesemiconductor substrate 100, a gate insulating film 210 formed on thesemiconductor body 110, a floating electrode 300 formed on the gateinsulating film 210 and the isolation insulating film 200, a controlelectrode 310 formed on the isolation insulating film 200 to face and behorizontally separated from at least one side surface of the floatingelectrode 300, a sensing material layer 40 formed between the controlelect rode 310 and the floating electrode 300, and source/drain regionsformed in the semiconductor body 110 with the floating gate 300interposed therebetween, wherein the isolation insulating film 200 isformed on a lower side surface of the semiconductor body 110 such thatthe semiconductor body 110 protrudes, and the floating elect rode 300 isformed, to surround, the semiconductor body 110 protruding on theisolation insulating film 200 with the gate insulating film 210interposed therebetween. The floating electrode 300 is formed tosurround the semiconductor body 110 protruding in a FIN shape, and thus,the width of the channel is increased, so that a drain current isincreased. Therefore, it is possible to improve the sensitivity of thesensor.

In the FET-type sensors 80, in the case where the cross-sectionalstructures (the cross-sectional structures taken along line A-A′) of theFET-type sensors 80 are different even though the same material is usedto form the sensing material layers 40, the operation sensing mechanismsare different, and thus, the sensing materials may be different. On thecontrary, in the case where the sensing material layers 40 of theFET-type sensors are different even though the cross-sectionalstructures of the FET-type sensors 80 are the same, the operationsensing mechanisms are different, and thus, the sensing materials may bedifferent.

The FET-type sensor array according to the first embodiment of theinvention includes two or more FET-type sensors SO having a change incapacitance caused from a change in dielectric constant or a change inwork function as a operation sensing mechanism and having at least oneor more sensing materials.

Even in the case where the sensing mechanisms are applied to the samesensing material layer 40, the sensing mechanisms may has differentsensing characteristics (referred to as sensing fingerprints) for aspecific material to be sensed. Therefore, without using a large numberof sensing materials, it is possible to accurately sense the types andthe concentrations of materials to be sensed.

In the FET-type sensor array according to the first embodiment of theinvention, one or more sensors which are at least one or more ofresistance-type and capacitance-type sensors may be arranged to beadjacent to the FET-type sensor 80,

As illustrated in FIG. 3, unlike the related art where sensors having abuilt-in micro-heater are arranged in arbitrary intervals of rows or/andcolumns, a sensor array according to a second embodiment of theinvention is configured to include a plurality of FET-type sensors 80having a horizontal floating electrode 300, a built-in heater 500, andan air layer 600 formed in a semiconductor substrate ICQ at the lowerend of an isolation insulating film 200 in a region including a sensingmaterial layer 40, the FET-type sensors are arranged at arbitrarydistances from one reference point, and the same areas 630 (for example,control electrodes) of the FET-type sensors 80 are formed to face thereference point. The same area may be a control elect rode or may be acontrol electrode that can be used as a micro-heater.

The FET-type sensors 80 constituting the sensor array according to theembodiment include the FET-type sensors 80 disclosed in Patent Documents2 and 3. In particular, as illustrated in FIGS. 4A to 4D, the FET-typesensors include a sensor having a micro-heater 50 and an air layer 600having a change in dielectric constant of a sensing material layer 40according to presence or absence of a to-be-sensed material as aoperation sensing mechanism. Besides, the FET-type sensors include asensor having a change in work function as a operation sensingmechanism. In the sensor having the operation sensing mechanism, amicro-heater 50 may be operated in common with the control electrode 310or operated separately from the control electrode 310.

In particular, FIG. 4D illustrates a structure of a three-dimensionalFin-FET-type sensor disclosed in Patent Document 3. As described, in thefirst embodiment, a floating electrode 300 is formed to surround asemiconductor body 110 protruding in a FIN shape to enlarge a width of achannel to increase a drain current, so that the Fin-FET-type gas sensorhas an advantage of increasing the sensitivity of the sensor.

In the FET-type sensors 80, in the case where the cross-sectionalstructures (the cross-sectional structures taken along line A-A′) of theFET-type sensors 80 are different even though the same material is usedto form the sensing material layers 40, the operation sensing mechanismsare different, and thus, the sensing materials may be different. On thecontrary, in the case where the sensing material layers 40 of theFET-type sensors are different even though the cross-sectionalstructures of the FET-type sensors 80 are the same, the operationsensing mechanisms are different, and thus, the sensing materials may bedifferent.

The FET-type sensor array according to the second embodiment of theinvention includes two or more FET-type sensors 80 having a change incapacitance caused from a change in dielectric constant or a change inwork function as an operation sensing mechanism and having at least oneor more sensing materials.

Even in the case where the sensing mechanisms are applied to the samesensing material layer 40, the sensing mechanisms may has differentsensing characteristics (referred to as sensing fingerprints) for aspecific material to be sensed. Therefore, without using a large numberof sensing materials, it is possible to accurately sense the types andthe concentrations of materials to be sensed.

In the FET-type sensor array according to the second embodiment of theinvention, one or more sensors which are at least one or more ofresistance-type and capacitance-type sensors may be arranged to beadjacent to the FET-type sensor 80. The resistance-type orcapacitance-type sensor in the related art includes a micro-heater 50separated by an insulating film 200 at the lower end thereof and an airlayer 600 formed in a semiconductor substrate 100 at the lower end of anisolation insulating film 200 to surround the sensing material layer 40.

A sensor array according to a third embodiment of the invention is anexample of the sensor array according to the first embodiment of theinvention. As illustrated in FIG. 5A, a plurality of the FET-typesensors 80 are arranged in a shape of a circle having a certain radiusfrom the reference point, and the same areas 630 of the FET-type sensors80 are arranged to face the reference point.

A sensor array according to a fourth embodiment of the invention is anexample of the sensor array according to the first embodiment of theinvention. As illustrated in FIG. 5B, a plurality of the FET-typesensors 80 are arranged in a shape of an ellipse, and the same areas 630of the FET-type sensors 80 are arranged to face the reference point.

A sensor array according to a fifth embodiment of the invention is anexample of the sensor array according to the first embodiment of theinvention.

As illustrated in FIG. 5C, a plurality of the FET-type sensors 80 arearranged in a rectangular shape, and the same areas 630 of the FET-typesensors 80 are arranged to face the reference point.

A sensor array according to a sixth embodiment of the invention is anexample of the sensor array according to the first embodiment of theinvention. As illustrated in FIG. 5D, a plurality of the FIT-typesensors 80 are arranged in a rectangular shape. The same areas 630 ofthe FET-type sensors 80 are arranged to face the reference point and tobe deviated by arbitrary angles from lines connecting the referencepoint and the centers of the FET-type sensors 80. The angle θ betweenthe line connecting the reference point and the center of the FET-typesensor 80 and the line connecting the center of the same area 630 andthe center of the FET-type sensor 80 satisfies 0°=<θ<90°.

A sensor array according to a seventh embodiment of the invention is anexample of the sensor array according to the second embodiment of theinvention. As illustrated in FIG. 6A, a plurality of the FET-typesensors 80 are arranged in a shape of a circle having a certain radiusfrom the reference point, and the micro-heaters 50 of the FET-typesensors 80 are arranged to face the reference point.

A sensor array according to an eighth embodiment of the invention is anexample of the sensor array according to the second embodiment of theinvention. As illustrated in FIGS. 6B and 6G, a plurality of theFET-type sensors 80 are arranged in a shape of an ellipse, and themicro-heaters 50 of the FET-type sensors 80 are arranged to face thereference point. FIG. 6B illustrates an example where the micro-heaters50 are connected in series, one terminal of each micro-heaters 50 isapplied with a heater voltage V_(H), and the other terminal thereof isconnected to the ground. FIG. 6C illustrates an example where themicro-heaters 50 are connected in parallel, one terminal of eachmicro-heaters 50 is applied with a heater voltage the other terminalthereof is connected to the ground, and the ground terminals of themicro-heaters 50 are shared as one,

A sensor array according to a ninth embodiment of the invention is anexample of the sensor array according to the second embodiment of theinvention. As illustrated in FIGS. 6D and 6E, a plurality of theFET-type sensors are arranged in a shape of a rectangle, and themicro-heaters 50 of the FET-type sensors 80 are arranged to face thereference point. FIG. 6D illustrates an example where the micro-heaters50 are connected in series, one terminal of each micro-heaters 50 isapplied with a heater voltage V_(H), and the other terminal thereof isconnected to the ground, FIG. 6E illustrates an example where themicro-heaters 50 are connected in parallel, one terminal of eachmicro-heaters 50 is applied with a heater voltage V_(H), the otherterminal thereof is connected to the ground, and the ground terminals ofthe micro-heaters 50 are shared as one.

A sensor array according to a tenth embodiment of the invention is anexample of the sensor array according to the second embodiment of theinvention. As illustrated in FIGS. 6F and 6G, a plurality of theFET-type sensors 80 are arranged in a rectangular shape, themicro-heaters 50 of the FET-type sensors 80 are arranged to face thereference point and to be deviated by arbitrary angles from linesconnecting the reference point and the centers of the FET-type sensors80. The angle θ between the line connecting the reference point and thecenter of the FET-type sensor 80 and the line connecting the center ofthe micro-heater 50 and the center of the FET-type sensor 80 satisfies0°=<θ<90°. FIG. 6F illustrates an example where the micro-heaters 50 areconnected in series, one terminal of each micro-heaters 50 is appliedwith a heater voltage V_(H), and the other terminal thereof is connectedto the ground. FIG. 6G illustrates an example where the micro-heaters 50are connected in parallel, one terminal of each micro-heaters 50 isapplied with a heater voltage V_(H), the other terminal thereof isconnected to the ground, and the ground terminals of the micro-beaters50 are shared as one.

In the sensor arrangement method of the sensor arrays according to thefirst to tenth embodiments, in comparison with the sensor arrayincluding sensors having micro-heaters in the related art where thesensors are arranged in rows or/and columns, the total area occupied bythe sensor array is small, and the micro-heaters 50 built in the sensorsare arranged to be close to each other, and thus, the sensing materiallayers 40 can be heated by the adjacent micro-heaters 50. Therefore,there is an advantage in that the total power consumption can also bereduced.

In the sensor arrays according to the first to sixth embodiments, thecontrol electrode 310, the micro-heater 50, the source/drain electrode320, the active region 120, and other regions constituting the FET-typesensor 80 are included in the same area 630 of the FET-type sensor 80.

A sensor has the optimum temperature at which the sensitivity of thesensor is maximized for each sensing material and each material to besensed. Therefore, in the case where two or more different sensingmaterials are applied to each of the sensor arrays according to thesecond and seventh to tenth embodiments, the line widths of themicro-heaters 50 built in the sensors may be designed differentlyaccording to the optimum temperatures of reaction of the sensingmaterials, so that the resistance can be different.

In the sensor arrays according to the second and seventh to tenthembodiments illustrated in FIGS. 6A to 6G, combinations of theresistance values R₁ to R_(n) of the micro-heaters 50 are available asfollows. All the resistance values are equal to each other (R₁=R₂=R₃=. .. R_(n)) all the resistance values are different from each other(R₁≠R₂≠R₃≠. . . R_(n)); and some of the resistance values are equal toeach other and the others are different from each other (R₁=R₂=. . .R_(n-1)≠R_(n), R₁=R₂=R_(n-2)≠R_(n-1)R_(n)).

In the sensor arrays according to the second and seventh to tenthembodiments, all the micro-heaters 50 built in a plurality of thesensors may be connected in series or in parallel, or an arbitrarynumber of some of the micro-heaters 50 built in a plurality of thesensors may be connected in series or in parallel.

In the sensor arrays according to the second and seventh to tenthembodiments, in the FET-type sensor including the micro-heater 50operated separately from the control electrode 310, the source electrode320 of the FET-type sensor the one end of the micro-heater 50 built ineach FET-type sensor may be separated as illustrated in FIG. 7A or maybe shared with one common electrode 330 as illustrated in FIG. 7B.

As illustrated in FIGS. 8A and 8B, in the sensor arrays according to thesecond and seventh to tenth embodiments, the line widths of the sensingmaterial layers 40 of FET-type sensors and the line widths of themicro-heaters 50 in the peripheries of the sensing material layers 40are configured to be larger than the line widths of the micro-heaters 50arranged in the regions other than the sensing material layers 40 andthe peripheries of the sensing material layers 40, and thus, the heatgenerated is reduced, so that it is possible to reduce loss of heat.

As illustrated in FIGS. 9A and 9B, in the sensor arrays according to thesecond and seventh to tenth embodiments, in order to prevent themicro-heaters 50 from being physically disconnected and destructed bythe heat generated from the contact holes 70 for electrically connectingthe micro-heaters 50 and the metal wires 311, the number of contactholes 70 is configured to be sufficiently large, and thus, the totalcontact area is increased, so that it is possible to improve themechanical stability.

As illustrated in FIGS. 10A and 10B, in the sensor arrays according tothe second and seventh to tenth embodiments, in the case where thecontrol electrode 310 is a metal, the material 90 having a thermalconductivity lower than that of the metal is connected to a region ofthe control electrode 310 through the contact hole 70 and arranged witha predetermined length, and the metal wire 311 is connected through thecontact hole 70 provided at the end of the material 90 having lowthermal conductivity. As the material 90 having a thermal conductivitylower than that of the metal, there may be exemplified polysilicon. Thematerial 90 having low thermal conductivity is additionally arrangedbetween, the control electrode 310 made of a metal and the metal wire311, so that there is an advantage in that loss of heat generated fromthe micro-heaters 50 through the metal wire 311 can be reduced.

In this case, since the two connection portions are electricallyconnected through the contact hole 70, there is no problem in gating thecontrol electrode 310 for the operation of the sensor.

In the sensor arrays according to the second and seventh to tenthembodiments, the region of the air layer 600 functioning to reduce theloss of heat of the micro-heater 50 built in each FET-type sensor alwaysincludes the sensing material layer 40. The formation process for theair layer 600 is performed by anisotropically etching the isolationinsulating film 200 below the undercut pattern 610 by dry etching or wetetching using a gas such as CF₄, and subsequently by isotropicallyetching the semiconductor substrate 100 below the isolation insulatingfilm 200 by dry etching or wet etching using a gas such as SF₆.

The undercut pattern 610 is an open pattern and may be formed byselecting one of shapes including a circular, an ellipse, a square, asquare having rounded corners, a rectangle, a rectangle having roundedcorners or may be formed by selecting one of shapes including anellipse, a rectangle, and a rectangle having rounded corners andincluding at least one region that is bent at an arbitrary angle in themiddle. In particular, as illustrated in FIGS. 11A and 11B, the width ofthe undercut pattern 610 is configured to be sufficiently thin so that,when the sensing material layer 40 is formed by a method such as Inkjetprinting, the amount of sensing material that is lost through the airlayer 600 is reduced and the sensing material is well deposited betweenthe floating electrode 300 and the floating electrode 300. Namely, it ispossible to obtain the effect of increasing the sensor production yield.The undercut pattern 610 is designed to be arranged as close as possibleto the micro-heater 50, so that the active region 120 of the sensor isnot damaged while the semiconductor substrate 100 is etched to form, theair layer 600. Therefore, it is possible to obtain the effect, ofensuring mechanical stability. Finally, an anchor 620 between theundercut pattern 610 and another adjacent, pattern, is allowed toremain, so that the sensor can be prevented from collapsing toward thesemiconductor substrate 100 after the etching of the air layer 600.

As illustrated in FIGS. 11A and 11B, the undercut patterns 610 areformed in the peripheries of the control, electrodes 310 arranged in theregions other than the sensing material layers 40 and the peripheriesthereof, between the floating electrode 300 and the active region 120,and in the peripheries of the portions where the micro-heaters 50 andthe metal wires 311 are connected to the contact holes 70, and thus theloss of heat of the micro-heater 50 is minimized.

As illustrated in FIGS. 12A and 12B, in the sensor array according tothe fifth embodiment of the invention, two sensors of the sensor arrayaccording to the second embodiment are included, the two sensors areformed as close as possible, and the undercut pattern 610 and the anchor620 for mechanical stability of the sensor array are included betweenthe two sensors, FIG. 12A illustrates the sensor array to which the samesensing material is applied, and the micro-heaters 50 have the same linewidth. FIG. 12B illustrates the sensor array to which different sensingmaterials are applied, and the micro-heaters 50 have different linewidths.

As illustrated in FIGS. 5A to 11B, other features of the sensor arrayaccording to the fifth embodiment include all the features described inthe second and seventh to tenth embodiments.

A sensor array according to the invention can be implemented by simpleprocesses and can be easily combined with existing CMOS processes, sothat industrial applicability is high.

In particular, the sensor array according to the invention has a higherdegree of integration than that of a sensor array developed in therelated art, production yield is high, manufacturing cost is low, thesensor array can be driven with low power, and the sensor array can beusefully applied for various sensor fields of gas sensors, chemical andbiological sensors, and the like.

While the: present invention has been particularly illustrated, anddescribed, with reference to exemplary embodiments thereof, it should beunderstood by the skilled in the art that the invention is not limitedto the disclosed embodiments, but various modifications and applicationsnot illustrated in the above description can be made without departingfrom the spirit of the invention. In addition, differences relating tothe modifications and applications should be construed as being includedwithin the scope of the invention as set forth in the appended claims.

What is claimed is;
 1. An FET-type sensor array comprising; a pluralityof FET-type sensors which are arranged at arbitrary distances from onereference point, wherein the FET-type sensor includes: a semiconductorsubstrate; a semiconductor body formed to protrude from thesemiconductor substrate; an isolation insulating film formed on a sidesurface of the semiconductor body; a gate insulating film formed on thesemiconductor body; a floating electrode formed on the gate insulatingfilm and the isolation insulating film; a protective insulating filmformed at least on the floating electrode; a control electrode formed toface and be horizontally separated from at least one side surface of thefloating electrode; a sensing material layer arranged on the controlelectrode and at least horizontally opposing sidewalls of the floatingelectrode, the sensing material layer being arranged to the floatingelectrode with the protective insulating film interposed therebetween;and source/drain regions formed in the semiconductor body with thefloating electrode interposed therebetween, and wherein the same areasof the FET-type sensors are arranged to face a reference point.
 2. TheFET-type sensor array according to claim 1, wherein the sensing materiallayers lot a plurality of the FET-type sensors are made of a pluralityof sensing materials having different compositions, and each sensingmaterial is applied to one or more FET-type sensors.
 3. The FET-typesensor array according to claim 1, wherein the control electrode isformed on the isolation insulating film to have a specific length and isused as a micro-heater, wherein the protective insulating film is formedat least on the floating electrode and the control electrode, andwherein the FET-type sensor further includes an air layer formed atleast below the isolation insulating film that is in contact with thecontrol electrode.
 4. The FET-type sensor array according to claim 3,wherein the sensing material layers of a plurality of the FET-typesensors are made of a plurality of sensing materials having differentcompositions, and each sensing material is applied to one or moreFET-type sensors,
 5. The FET-type sensor array according to claim 3,wherein the control electrodes used as the micro-heaters of a pluralityof the FET-type sensors are arranged to be adjacent to each other, andthus, the sensing material layer in each FET-type sensor is heated bythe control electrode of each FET-type sensor and the control electrodeof the adjacent FET-type sensor, or the control electrode used as themicro-heater of each FET-type sensor is formed to face a referencepoint, so that power consumption is reduced.
 6. The FET-type sensorarray according to claim 3, wherein the control electrodes of aplurality of the FET-type sensors are connected to each other in seriesor in parallel, or some of the control electrodes are connected to eachother in series and the others of the control electrodes are connectedto each other in parallel, and wherein line widths of the controlelectrodes used as the micro-heaters are equal to each ether or the linewidth is changed depending on each FET-type sensor.
 7. The FET-typesensor array according to claim 3, wherein the FET-type sensor furtherincludes: metal wires which are in electric contact with the controlelectrodes; and a plurality of contact holes which are formed betweenthe control electrodes and the metal wires, and wherein the line widthsof the sensing material layers and the control electrodes in theperipheries thereof in the sensor array are formed to be smaller thanthe line widths of the control electrodes in the remaining areas.
 8. TheFET-type sensor array according to claim 3, wherein the FET-type sensorfurther includes an undercut pattern for forming an air layer, andwherein the undercut pattern is formed to have one of shapes including acircle, an ellipse, a square, a square having rounded corners, arectangle, a rectangle having rounded corners or formed to have one ofshapes including an ellipse, a rectangle, and a rectangle having roundedcorners and include one or more regions that are bent at arbitraryangles in the middle.
 9. The FET-type sensor array according to claim 1,wherein the control electrode is formed to have a specific length isused as a micro-heater, and wherein the FET-type sensor further includesan air layer formed at least below art isolation insulating film whichis in contact, with the control electrode.
 10. The FET-type sensor arrayaccording to claim 9, wherein the sensing material layers of a pluralityof the FET-type sensors are made of a plurality of sensing materialshaving different compositions, and each sensing material is applied toone or more FET-type sensors.
 11. The FET-type sensor array according toclaim 9, wherein the control electrodes used as the micro-heaters of aplurality of the FET-type sensors are arranged to be adjacent to eachother, and thus, the sensing material layer in each FET-type sensor isheated by the control electrode of each FET-type sensor and the controlelectrode of the adjacent FET-type sensor, or the control electrode usedas the micro-heater of each FET-type sensor is formed to face areference point, so that power consumption is reduced.
 12. The FET-typesensor array according to claim 9, wherein the control electrodes of aplurality of the FET-type sensors are connected to each other in seriesor in parallel, or some of the control electrodes are connected to eachother in series and the others of the control electrodes are connectedto each other in parallel, and where line widths of the controlelectrodes used as the micro-heaters are equal to each other or the linewidth is changed depending on each FET-type sensor.
 13. The FET-typesensor array according to claim 9, wherein the FET-type sensor includes:metal, wires which are in electric contact with the control electrodes;and a plurality of contact holes which are formed between the controlelectrodes and the metal wires, wherein the line widths of the sensingmaterial layers and the control electrodes in the peripheries thereof inthe sensor array are formed to be smaller than the line widths of thecontrol electrodes in the remaining areas, and wherein, in the casewhere the control electrode that is in contact with the sensing materiallayer is made of metal, a material having a thermal conductivity lowerthan that of a metal is connected through contact holes provided at bothends of the control electrode and arranged with a predetermined length,and a metal wire is connected through contact holes provided at bothends of the material having low thermal conductivity.
 14. The FET-typesensor array according to claim 9, wherein the FET-type sensor furtherincludes an undercut pattern for forming an air layer, and wherein theundercut pattern is formed to have one of shapes including a circle, anellipse, a square, a square having rounded corners, a rectangle, arectangle having rounded corners or formed to have one of shapesincluding an ellipse, a rectangle, and a rectangle having roundedcorners and include one or two regions that are bent at arbitrary anglesin the middle.
 15. The FET-type sensor array according to claim 1,wherein the FET-type sensor further includes: a micro-heater formed witha predetermined length on the isolation insulating film to face and behorizontally separated from at least one side surface of the floatingelectrode; and an air layer formed at least below the isolationinsulating film that is in contact with the micro-heater, wherein theprotective insulating film is formed at least on the floating electrodeand the micro-heater, and wherein the micro-heater of each FET-typesensor is formed to face the reference point.
 16. The FET-type sensorarray according to claim 15, wherein the sensing material layers of aplurality of the FET-type sensors are made of a plurality of sensingmaterials having different compositions, and each sensing material isapplied to one or more FET-type sensors.
 17. The FET-type sensor arrayaccording to claim 15, wherein the micro-heaters of a plurality of theFET-type sensors are arranged to be adjacent to each other, and thus,the sensing material layer in each FET-type sensor is heated by themicro-heater of each FET-type sensor and the micro-heater of theadjacent. PET- type sensor, so that power consumption is reduced. 18.The FET-type sensor array according to claim 15, wherein themicro-heaters of a plurality of the FET-type sensors are connected toeach other in series or in parallel, or some of the micro-healers areconnected to each other in series and the others of the micro-heatersare connected to each other in parallel, and wherein the line widths ofthe micro-heaters are equal to each other or the line width is changeddepending on each FET-type sensor.
 19. The FET-type sensor arrayaccording to claim 15, wherein the FET-type sensor further includes: ametal wire which, is in electric contact with the micro-heater; and aplurality of contact holes which are formed between, the micro-heaterand the metal wire, wherein the line widths of the sensing materiallayers and the micro-heaters in the peripheries thereof in the sensorarray are formed to he smaller than the line widths of the micro-heatersin the remaining areas, and wherein, in the case where the controlelectrode that is in contact with the sensing material layer is made ofmetal, a material having a thermal conductivity lower than that of ametal is connected through contact holes provided at both ends of thecontrol electrode and arranged with a predetermined length, and a metalwire is connected through contact holes provided at both ends of thematerial having low thermal conductivity.
 20. The FET-type sensor arrayaccording to claim 15, wherein the FET-type sensor further includes anundercut pattern for forming an air layer, and wherein the undercutpattern is formed to have one of shapes including a circle, an ellipse,a square, a square having rounded corners, a rectangle, a rectanglehaving rounded corners or formed to have one of shapes including anellipse, a rectangle, and a rectangle having rounded corners and includeone or more regions that are bent at arbitrary angles in the middle.